Vine lets you capture and share video limited to six seconds in length. It’s perfect for the ADD generation, and naturally suited to the content that really powers the Web: cat videos.

Vine’s success reportedly has spurred Instagram to move ahead with plans that have been in the works for two year to add video, according to AllThingsD. Although it’s not yet known just how it will work or how long the videos will be, one report says internal tests at Facebook put the length at between 5-10 seconds long.

In the wake of what happened at Flickr, how will Instagram’s users react to this change? The AllThingsD report lays out the pitfalls:

Part of the appeal of Instagram as it stands today lies in its simplicity. Scroll down the ever-flowing cascade of photos in your stream and the movement is seamless, easy to ingest. Its elegance and ease of use is one of the key reasons why Instagram has seen such a rapid growth curve over its short lifespan.

The introduction of video directly into the stream could break up that simple flow, potentially putting off many who have come to love the ease of moving quickly through the feed. Think of the time it takes to look at a photo and that low threshold for attention is exactly what makes them so easy (and addictive) to consume.

It’s likely the integration will look a lot like Vine, which actually is similar to the layout of Instagram. You scroll horizontally on your phone through videos created by you and your friends, and as each is centered on the screen, it begins playing. Since each video only lasts six seconds, it’s not too intrusive.

But what will the experience be like if you’re scrolling through a mix of stills and video? Would it be wise to have video start auto-playing, or should it require a tap? Or, should video be displayed in a separate tab on the phone, which might mean fewer views? If you’re used to only viewing photos on Instagram, would you ever tap a video tab?

If the video reports are accurate, it will be interesting to see how Instagram’s user base handles the new feature. If you use Instagram, how do you feel about the addition of video?

“Serious” photographers often use Flickr for business purposes, and a slowdown can have a material impact. I don’t know of any serious photographers that use instagram for business reasons (many do use it for fun), so I would agree, it is likely a non-issue.

Nobody likes change. No matter what social network you are talking about, change is always frowned upon for a short period of time. Then, users start to adapt to the changes and all is forgiven. I’d guess that would be what happens here.

I think it’s a smart move on Instagram’s part. The only reason I have an account is to follow what my middle school daughter posts. She takes pictures, adds captions/effects–incredible things. She has several apps to make videos on her phone/iPad–and the ability that kids now have to create videos is amazing. What my daughter and her friends can do in 30 minutes is mindblowing–it’s a full blown music video (using music they already own on iTunes). Instagram obviously knows its target audience. They live in the video/photo world.